FGF-9 is a heparin binding growth factor that belongs to the FGF family. Proteins of this family play a central role during prenatal development and postnatal growth and regeneration of a variety of tissues, by promoting cellular proliferation and differentiation. FGF-9 targets glial cells, astrocytes cells and other cells that express the FGFR 1c, 2c, 3b, 3c, and 4. Recombinant murine FGF-9 is a 23.3 kDa protein containing 205 amino acid residues.